Fuel pump



G. M. ROGERS May 1, 1951 FUEL PUMP 5 Sheets- Sheet 1 4 w C: W. 3 5 4 3 j3 gessssss F m E I V 7 H H W E u AIIHIIIIII v h 511 A f ssssss v m 4 3OJ Z Z c Z 8 a 4 2&% 0 z 6 7 9 z Z 8 3 INVENTOR GHRDINER M. ROGERS AORNEY y 1951 G. M. ROGERS 2,551,053

' FUEL PUMP Filed Dec. 6, 1946 5 Sheets-Sheet 4 INVENTOR GARDINER M.Rom-1R5 A ORNEY Patented May 1, 1951 UNITED STATES PATENT OFFICE FUELPUMP Gardiner M. Rogers, Ithaca, N. Y.

Application December 6, 1946, Serial No. 714,553

14 Claims.

tive-stroke adjustment helix cavity or edge op-' eratable for fuelquantity adjustment as by a fuel rack connected with the plunger, whichhelix, in cooperation with lateral ports in the cylinder, ispositionable to vary the amount of fuel introduced to the engine duringuniform length strokes of the plunger. In the usual fuel injector pumpof that class, commonly known as a jerk pump, a substantially fixedvolume of fuel isdelivered to the associated engine cylinder orcombustion space for each rack setting irrespective of engine speed.When a unitinjector jerk pump is used with a fixed injector nozzleorifice (or with fixed nozzle orifices) variation in the fuel injectiorfpressure is controlled principally by engine operating speed. After theusual delivery valve is opened, the injection pressure (neglectingleakage) is controlled solely by engine operating speed. Since injectioncannot take place until the delivery valve is opened, it is factual tosay that with the usual jerk pump (neglecting the factor of leakage)injection pressure rises as a function of increase in engine speed.Since spray pattern and atomization (again assuming fixed nozzleorifices) are controlled by the pressure in the nozzle, both areinflexibly tied to engine speed in the usual jerk pump.

A different type of injector pump falling in the same general class ismade the subject matter of my application Serial No. 608,588, filedAugust 2, 1945. In that injector pump a controlled or regulated pressureis built up in the pressure chamber of the pump before the pressurechamber is communicated with the atomizing nozzle, and substantiallythat pressure is maintained thereafter during the working stroke 1 ofthe pump. Injection starts, during maintenance of controlled pressure,upon opening of the delivery port and whatever check valve may be usedbetween said port and the nozzle. The volume of fuel normally deliveredto the nozzle per plunger stroke of a given length is essentially acombined function of the capacity of the injector nozzle orifices toconvey fuel to the combustion chamber and of the pressure control orregulating means in venting or by-passing part of the displacementcapacity of the pump. The present invention as illustrated is embodiedwith an injector pump of such controlled injection pressure type; andanother object is to pro- 2. vide an improved injector mechanism of thattype.

In my said application, the injection pressure control is shown in theform of a small fuel bypass port or vent for the pressure chambercommunicating therewith through the bushing or cylinder of the pump anda spring closed valve in the form of a metal ring bearing at one sideagainst a plug for the pressure control port, said plug being in theform of a smooth steel ball. Calibrated tension of the spring limits thepressure which can be built up in the pressure chamber thus modifyingthe inherent tendency for the pressure to rise with increased engineoperating speed. In the system, according to my said application, theapparatus was found inadequate to perform efficientl over as great aspeed range as required for some types of operation.

One difficulty experienced with the controlled pressure injector pump asoutlined above arose from the fact that in order to maintain the volumeof injected fuel required to maintain high speed under load it was foundnecessary to de crease the part of each pump charge of fuel spilledthrough the pressure control port at high speeds, thus gaining thedesired volume at those speeds. The pressure control port in thecylinder wall could not be decreased in diameter indefinitely for thepurpose of restricting the volume so spilled, partly because ofmanufacturing limitations and partly because that port, in serving as arestricted vent for surplus fuel in building up injection pressure priorto the beginning of delivery to the nozzle, would, if made extremelysmall, create excessively high pressures in the pump operating mechanismand excessive strain on the pump plunger and cylinder and theiroperating means after the supply port of the pump is closed and beforethe delivery port is opened.

Since the volume of injected fuel at a given fuel setting falls off toorapidly for as high a power attainment at high speed as sometimesdesired, the present invention was developed primarily to enable thepractical attainment of higher controlled pressure in the pump and,concomitantly, to cause greater proportional shares of the pump fueldisplacement per stroke to be delivered efficiently to the combustionspace of the engine at high speed without sacrifice of satisfactoryengine performance at lower speeds.

The embodiment of the present invention illustrated herewith comprisesprimarily the provision of a pressure control relief clearance betweenthe pump plunger and its effective bore surface, which clearance willoperate to control efliciently the pressure in the pressure chamberprior to injection and during injection at the various operating speeds(and loads) required, for example, in the use of Diesel type engines todrive vehicles.

3 The specific speed control mechanism shown, comprises a relief area ofa few ten thousandths of an inch deep, radially of the plunger,preferably formed by removing asmall amount of the plunger land surfaceadjacent to and intersecting a control edge of the plunger so that therelief gap acts in series with the pressure control port and withdifferent operative effects as speed is increased with a given racksetting to the end that the fuel delivered to the injector nozzle andthat vented by the control means is proportionately different atdifferent engine speeds. The

radially shallow relief gap of considerable breadth will hereinafterusually be referred to as a. control band, indicating an annulus orfragment thereof which may extend wholly or par-- tially in any desireddirection relative to the axis of the plunger.

The pressurecontrol relief area maybe positioned to communicate with thepressure control port for the entire high to low fuel setting or anyportion of the range of fuel settings. The relief area may intersect anycavityor fuel port closing or spill edge portion of the" plungerwhichcommunicates with the pump pressure chamber; and the relief portmay sometimes serve other functions, e. g. ordinary spill. Also theradial depth of the' relief area may vary at different regionscircumferentially of the plunger and/or-axially of the plunger.

Other objects and features of the invention will become apparent fromthe following description of the exemplary embodiments shown by theaccompanying drawing, wherein:

Fig. l is a longitudinal central assembly view of a unit injectorincorporating the present invention in one form;

Fig. 2 is a similar fragmentary View on a larger scale showing thepresent invention used in. series with the pressure control valvesubstantially according to my said prior application;

Fig. 3 is a relatively enlarged fragmentary central sectional view ofthe piston and valving end of the pump plunger according to Fig. 1 andassociated portions of the cooperating cylinder;

Fig. 4 is a transverse sectional view through the injector plungerandcylinder as indicated-by the line l4 on Fig. 1;

Figs. 5 and 6 are diagrammatic representations of developments of theplunger and cylinder'surfaces and typical arrangements of cooperatingrecesses and ports intersecting respective surfaces.

Figs. 7' to 10 inclusive, are superimposed developrnent diagrams of theplunger and cylinder, showing difierent axial relationships between theplunger and cylinder surfaces (ports, cavities, etc.) with the plungeradjusted for full or maximum fuel delivery;

Figs. 11 and 12 are views similar to Figs. '7 to 10, showing the plungeradjusted to a low idlin speed position;

Figs. 13 to 15 inclusive, are views similar to the foregoing (e. g. 11and 12) showing the plunger adjusted to an initial no fuel position;

Fig. 16 is a similar view showing the'maximum no fuel positionadjustment of the plunger.

Referring to Fig. 1 showing a unit type of injector pump mechanism, anengine-operated plunger piston I slidably fitting a pump cylinder 2,usually referred to in the art as a. bushing, is reciprocated in amanner to receive fuel into a pressure chamber P of the cylinder from afuel cavity or reservoir 3 through suitable supply port means duringsuccessive pump filling'or suction strokes of the plunger and to delivercharges of fuel to a combustion space of the engine through an atomizingnozzle assembly generally shown at 1 during uniform length: pressurestrokes of the plunger. The unit injector as shown herein includes amain body member 5 receiving, in a counterbore 5 thereof, a reduceddiameter upper portion of the pump cylinder or bushing 72. The body 5 isthreaded as at E for engagement with a sleeve-like nut l which entersthe associated engine cylinder. (not shown), as through the cylinderhead Water jacket, and supports the nozzle assembly 5 in communicationwith the combustion space of the cylinder. The sleevelike nut has ashoulder at 8 for engagement with a suitable gasket (not shown) around.an opening in the cylinder head, and an adjacent reduced diameterportion .9 which fits. a smaller bore in the cylinder head and is heldtherein by suitable means (not. shown) which engages the body 5 andforces the shoulder 8 against the cylinder head.

The fuel cavity or reservoir 3 is formed as an annular space between thebushing 2 and sleevelike nut 1, said space beinggenerally sealed at itstop end. The lower end face ll of the bushing Zabuts a coaxial basepiece or cylinder head in the form of a recessed block I2; The basepiece is one-of a plurality of stacked. centrally-apertured injectornozzle assembly parts. fixedly supported in and by the sleeve nut inmoreor less:

conventional arrangement- The fuel cavity 3 is supplied with liquid fuelunder the usual low pressurethrough a supply pipe l5 leading to a filterchamber [6 containing a filter unit l l. The outlet of-the. filtercommunicates with a supply ductl-B in the body 5 entering the upper endof the fuel cavity 3 The cylinder block 2 has a central cylinder bore2|, and, preferably, the pump cylinder has a plurality of radial supplyand spill ports 28 leading fromthefuel supply cavity. 3 to the pressurechamber portion P defined by the cylinder bore 2| and the lower endportion of the plunger The ports 28 lie just below the lower end of theplunger when the latter is inits raised position as shown in Figs. 1 and2. The lowerend of the cylinder 2! is closed by a central planar surfaceportion'of the base block or cylinder head 5200mplementary to thebushing end surface H The radial portsZQ cooperate for supply directlywith the chamber P and for spill with said chamber through theintermediary of a spill recess S in the periphery of the plunger.

Above the spill and supplyports 263 is a lateral fuel delivery port 23which is formed as .part of a nearly diametral cross bore. 24 in thecylinder drilled thereinto from the side of .the cylinder opposite thedelivery port. The delivery port 23 intersects a vertical delivery ductportion 23a. which, in turn, enters an annular cavity 231) at the top ofthe cylinder head or base block l2. Communicating with the annularcavity 23b and also formed in the block i2- is an oblique delivery ductportion 2-30, the lower end of which opens into a cavity 25 atth-e topofv an annular nozzle assembly section 25 abutted bythe lowerreduceddiameter end We of the block 12. The cavity 2-5 may contain check valve-(not shown) for preventing blow-back of products of combustion from theassociated engine cylinder into the pump chamber and supply space 3through the delivery duct at such times. as the delivery port is openbut not delivering fuelr The injector nozzle orifices 32 are formed in atubular fitting 21 having a counterbore recess at 28 communicating witha central bore 29 of the section 26. A counterbore or cavity 28 in thefitting 2'! should contain a check valve 313 of suitable form, normallyclosed by an appropriate spring. Below the valve 30 the valve chamber 28communicates with a central bore 31 of the fitting 21 from which theinjector nozzle orifices 32 extend generally radially and downwardlyinto communication with the engine cylinder.

The mechanism for adjusting the plunger l in causing different amountsof fuel to be injected per stroke of the plunger is intended to beconventional and comprises, as shown, a pinion 33 slidably keyed to ashank portion 34 of the plunger and a toothed rack 35 slidable in themain body member or block 5 of the injector pump under the control of agovernor or throttle mechanism connected with the rack by suitablelinkage not shown.

Referring further to the plunger l, a more than 360 degree developmentof which is shown in Fig. 5 (portions being repeated beyond the 360degree indicating lines) the lower effective edge of the plunger(defined by the upper margin of a lower chamfer on the plunger) on thedownward or pressure stroke of the plunger closes the supply ports 20,thus initially trapping a definite quantity of fuel in the pressurespace P of the cylinder. Said space, however, through a central bore 4!(Fig. 3) in the plunger and interconnected lateral bores 42 and 43communicates at all times with the spill cavity S and the delivery helixcavity D of the plunger. Both said cavities S and D are sufficientlydeep radially of the plunger so as not materially to restrict the freeflow of fuel to or from the central and cross passages of the plungerfor communication with whatever ports are opened during the plungerstroke. endless non-inclined annular trough intersecting the outersurface of the plunger, but in order better to accommodate spill fluidparticularly at the low speed and no-fuel settings of the plunger,partly to balance the cavity portions around the plunger, thus to assisthydraulically in centering of the plunger in its guide bore, and forother purposes hereinafter described, the cavity S is preferablyextended as at S to provide a supplemental or auxiliary spill cavity.The supplemental spill cavity as shown is helical, that is, parallel tothe delivery helix cavity D, and, in some cases, it may be formed as acontinuation of the delivery helix cavity as indicated in broken linesat 44 on Fig. 5 only. All the cavities S, S and D can be very simplyformed as end mill cuts in cooperation with appropriate tool guides.

Referring further to Fig. 5, the main delivery control helix cavity D isformed in a land portion 45 of the plunger extending, for example, aboutthree-quarters of the circumference of said land and comprising a lowerinclined control edge 49 and an upper control edge 50. The land 45 is,for the most part, of the same diameter as the land 46 separating thelower fuel cut off edge 40 from the lower effective edge 41 of the spillcavity S. The delivery helix cavity D is shown in full lines as closedat its ends by the circular milling cuts. The end cavity wall 5|designates the low fuel end of the cavity and 52 the high fuel endthereof. Near the low fuel end of the cavity there may be provided apreliminary injection relief as indicated by the broken line 53 whichrelief formsa. very slight The spill cavity S may be an indentation ofthe land 45 adjoining the edge 49 of the delivery helix cavity at thelow fuelportion thereof. While preliminary injection is desirable undercertain conditions at light loads; the relief 53 may be extended fartheralong the cavity D to cover any desired load. The function of thepreliminary injection relief is fully described in my said co-pendingapplication and forms no part of the present invention.

The transverse bore 24 in the cylinder or bushing 2 extends non-radiallyof the axis of the cylinder but intersecting the bore 2| on one sidethereof (lower side, as shown in Fig. 4) less than V degrees removedfrom the delivery port 23..

Such relative positioning of the ports 23 and 24a enables the rotationof the plunger for fuel adjustment more than 180 degrees. The bore 24avoids having to drill the delivery port 23 from the opposite side ofthe bushing and then having to plug the portion of the drilling radiallyoutwardly beyond the point of intersection with the vertical drillingwhich forms the delivery duct portion 23a. The bore 24 andcorrespondingly the delivery port 23 slant somewhat downwardlyparticularly to provide the auxiliary spill and pump filling port 24a,capable at times of opening into the spill cavity extension S increasingthe total spill port area and serving also to supplement the ports 20 infilling the pump pressure spaces (see Fig. 7) on the upward stroke ofthe plunger.

Additionally the auxiliary spill port 24a, through the supplementalspill cavity S, serves to by-pass, at low pressure, fuel displaced bythe plunger after closing of the main spill ports 23 and until pressurebuildup starts. Thus the small pressure control port 55 does not have toby-pass high pressure fuel until the pressure buildup period commences.This is desirable from the standpoint of minimizing on-useful. work,particularly at increased speeds. That in turn tends to minimize heatingof the fuel.

The particular, mutually parallel, arrange-- ment of the supplementalspill helix cavity 5" relative to the delivery helix cavity D enables:the portion of the plunger stroke devoted topressure buildu to beidentical in all fuel settings. The relationships between the supple--mental spill helix cavity S, the cooperating port. 24a and the deliveryhelix cavity D may be varied, as by changing the shape or position ofthe cavity S or the location of the port 24a to control the portion ofthe plunger stroke devoted to pressure buildup for any particular racksetting.

The formation of the delivery port 23 and aux iliary spill port 24anon-radially of the cylinder and somewhat slanting may be inexpensivelyand accurately accomplished by the use of appropriate jigs. To form thedelivery port 23 as a second drilling operation through the preformedauxiliary spill port, a cylindrical jig is placed inside the bushing 2and located by means of any suitable reference point so that the drillwhich forms the delivery port 23 will be properly guided to the exactrequired position and for intersection with the delivery duct portion23a as indicated in Fig. 4.. The bore 24 is always out of registrationwith the delivery helix cavity D whenever said cavity is desired tocommunicate with the delivery port 23. As illustrated by Fig. 11, theauxiliary spill port 24a remains active during low fuel settings freelyto vent fuel from the pressure chamber P into the supply space 3 aroundthe cylinder for a considerport 23, the fuel in the pressure space wouldbe completely trapped and the pump operating mechanism subjected tostrain. The duration of such fuel compression and strain on theoperating parts should be very short and probably of less duration thanindicated by Fig. 11. If in practice the duration of fuel compressionand strain prior to injection necessary to cause the desired initialinjection pressure becomes so short as to make manufacturing difficult,then a control band area completely encircling the plunger as indicatedby full lines in Fig. 11 provides a shallow relief area operating inconjunction with the relief port 55 to produce the control of initialinjection pressure.

Referring to Figs. 13 and 15 inclusive, these show the relationship ofplunger cavities and cylinder ports at an initial no fuel position ofthe plunger and during different portions of the pressure stroke. Fig.13 shows the main supply and spill ports 29 closed, but with theauxiliary port 24 still open to the spill cavity extension S. Fig. 14shows all the spill openings closed except the pressure control port 55which for the short interval between closing of the auxiliary spill port24a and opening of the main spill and supply ports 29 to the cavity Sfunctions to prevent generation of excessive pressures in the pump.

Fig. 15 shows the plunger at the bottom of the stroke.

Fig. 16 shows the relationship between the plunger and cylinder cavitiesand ports in a maximum shut-off position beyond that necessary to causecessation of injection.

I claim:

1. A fuel injector pump of the type having a pump cylinder and a plungerslidable therein, said plunger and cylinder cooperating to form apressure chamber and being relatively rotatable for adjusting themaximum volume of fuel that may be delivered per pressure stroke of thepump, said plunger having valving cavity means presenting a controlhelix edge cooperating with port means in the cylinder to begin andterminate each injection operation, a relief port in the cylinder and abroad passage of minute radial depth relative to the radial .depth ofthe cavity means formed between the cylinder bore and the plunger andcommunicating the pressure space with the relief port during at leastpart of the pressure stroke, said passage and port cooperating tocontrol the injection pressure in the pump during such part of thepressure stroke.

2. A fuel injector pump of the type having a pump cylinder and a plungerslidable therein, 'said plunger and cylinder cooperating to form apressure chamber and being relatively rotatable for adjusting themaximum volume of fuel that may be delivered per pressure stroke of thepump, said plunger having valving cavity means presenting a deliverycontrol helix edge arranged to open a delivery port in the cylinderto'start each injection operation, a relief port in the cylinder and abroad passage of minute radial depth relative to the radial depth of thecavity means formed between the cylinder bore and the plunger betweenthem which is rendered variably effective for fuel delivery adjustmentdepending upon the relatively turned position of the plunger andcylinder, a pressure control means for the chamber comprising a ventport communicating withthe cylinder bore and a relief area of greaterradial depth than ordinary working clearance but on that order formedbetween the plunger and cylinder and intersecting a valving edge of theplunger so as restrictedly to communicate the vent port with thepressure chamber during at least part of the pressure stroke of theplunger.

4. A fuel injector pump comprising a pump plunger with fuel adjustmentcavity means, said plunger being slidable in a cylinder and providingwith the plunger a pressure chamber continuously communicating with saidcavity means, a delivery port in the cylinder opened by an edge whichdefines part of the cavity means to commence injection at differentpoints in the plunger stroke depending upon the turned fuel-adjustingposition of the plunger, a pressure control relief area on the plungerof a radial depth on the order of ordinary working clearance butgreater, said area intersecting a port closing edge of the plunger andextending along such hedge circumferentially of the plunger, andcooperating vent port means intersecting the cylinder bore surface andpositioned to communicate with the relief area in a plurality of fueladjusting positions of the plunger and during at least part of thepressure stroke of the plunger.

5'. A fuel injector of the type wherein a cylinder and a plungerslidably fitting the same and forming a fuel pump are relativelyreciprocated to valve and force fuel under pressure to a nozzle andrelatively rotated to adjust the effective capacity of the pump;characterized by provision of a delivery port in the cylinder which portis opened by valving cavity means of the plunger during each pressurestroke to start injection, a

by-pass port in the cylinder, and a radially ex- 6. A fuel injector pumpof the type wherein a cylinder and a plunger, slidably fitting the sameand cooperating to form a pressure chamber are relatively reciprocatedto valve and force fuel under pressure to a nozzle, and relativelyrotated to adjust the maximum volume displaced per pressure stroke;characterized by provision of a pressure regulator by-pass port in thecylinder and yieldable means normally closing the port, and a restrictedpassagecomprising a very slightly reduced diameter portion of theplunger, said passage being in constant communication with the pressurechamber and extending along the plunger for communication with theby-pass port during at least part of each pressure stroke of the pump.

7. A fuel injector pump of the type wherein a cylinder and a plunger,slidably fitting the same and cooperating to form a pressure chamber arerelatively reciprocated to valve and force fuel under pressure to anozzle, and relatively rotated to adjust the maximum volume displacedper pressure stroke; characterized by provision of a delivery port inthe cylinder positioned to be '11 opened'tbya'valving cavity means in"the-plunger on each pressure stroke to startinj-ectioma pressureregulator by-pass port in the cylinder and 'yieldable meansnormally'closing the portgancl a restricted passage comprising a very'slightly reduced diameter portion of the plunger, .said passage beingin constant communication with 'the.pressure chamber and extendingalongthe plunger for communicaticn with the by -pass .port during atleast part of each pressure stroke of the pump.

,8.. A ;fuel injector pump comprising a plunger havinga delivery helixcavity and a cylinderfitting the plunger. and providing a pressure,chamberat one end Ztherefoff, the plunger being rotat- .able for fueladjustment, said cylinder having a ldeliveryport transverse to thecylinder axis .and registering with the helix cavity during a pressurestrokeof .the plunger to start injection, a

transverse bore in the cylinder wall opposite the vdelivery, port andaligned therewith, a generally horizontal spill cavity in the plungeraxially spaced from the delivery cavity, said cavitiesconstantlyeommunicating with each other and with the pressure chamber, asupply andspill portin .the. cylinder closed by the plunger during .apres- .sure stroke thereof totrapifuel in the pressure chamber andopened. by the spill cavity to .ter- .minate-injection nearthe end .ofsaid plunger stroke,;the spillcavityhaving a portion extended along theplunger towardthe delivery cavity, said transverse bore communicatingwith the .extended portion of the spill cavity-during no-fuel.andlow-fuel adjustments of the plunger.

.9. .Agfuel injector pump comprising .a cylinder closedatone end toprovide .a ,pressure chamber andhaving a common supply and spill portand a .delivery portin its wall, both. transverse to the axis. of thecylinder, a pump plunger slidably fitting thecy'linder, said plungerbeing rotationally adjustable for fuel setting and having radially.openintercommunicating cavity portions providing a. deliveryeportcontrolling edge. and. a separate spill-controlling edge, said cavityportions also communicating with the pressure chamber, relativelyrestricted pressure control means commimicatingwith. the pressurechamberprior to .andduring the time the. delivery port is opened, .saidpressure control meansbeing rendered operative by the plunger during itspressure stroke, and a. supplemental spill port inthe cylinder .op-

positethe delivery porttand positioned .to be .opened by onecf saidcavityportionsin amanner .todelay the, beginning of operation of thepressurecontroLmeans. during the pressure stroke loithe plungerandafterelosing of. the first menas pressure at .highspeeds causes slightdeflection :of .the cylinder or ,plunger, -.a portion of; said e xmean nof var ng lextentinthezdirec- .tlon .of. flow therethrou h .duringlsnchrelative "12 movementofthe'cylinder and plunger in said 'onedirection.

I1. In a fuel injector mechanism for internal combustion engines, a pumpcylinder and plung- '-erarranged for-relative reciprocating movement atdifferent-speeds'and cooperating to provide a pressure chamber, a feedport intersecting the cylinder and opened by a valving edge of theplunger during such relative movement in one direction to initiate fuelflow through the feed port, and pressure controlling vent means for thechamber whose venting area transverse to the direction of flowtherethrough is unaffected by variations in pump speed except aspressure at high speeds causes slight deflection of the cylinder orplunger.

'12. In a fuel injector mechanism for internal combustion engines, apump cylinder and plunger arranged for relative reciprocating movementat different speeds and cooperating to provide *a pressure chamber, afeed port intersecting the cylinder and opened by a valving edge of the"plunger during such relative movement in one direction to initiate fuelflow to an atomizing nozzle-orifice means connected to the feed port,and pressure controlling vent means for the chamber whose venting areatransverse to the direction'of flow therethrough is unaffected by-varia'tions-in pump speed except as pressure at high speeds causesslight deflection of the cylinder or plunger, said vent means providingan effective restriction to how of fuel therethrough which increasesduring the'pressure stroke of the pump at all pump speeds.

13. A fuel injector pump wherein a valving "and pumping plunger'andported cylinder cooperate to forma pressure chamber between them whichis'rendered variably efiective for fuel delivery adjustment from lowtoward high fuel settings depending upon the relatively turned positionof the plunger and cylinder, a pressure control vent means connectedwith the pressure chamber; the operative extent of which in thedirection of fuel flow increases according ,to 'the'fuel deliveryadjustment/from low toward high fuel settings.

'14. In a fuel injector mechanism for internal combustion engines, aported pump cylinder and valving plunger arranged for relativereciprocatingmovement and providing an injection pressure chamber,primary andsecondary pressure control restricted vent means operativelyassociatedwith the chamber and rendered operative by and during saidrelative movement in the fuelinjecting direction so that the primaryvent smeans alone .establishes an initial. chamber pres---sure..and'isubsequently the two means. act in :series .to establish ahigher injection pressure.

GARDINER M. ROGERS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,854,009 Wilkinson Apr. 12, 19321,966,694 Vaudet et al. July 1'7, 1934 2,096,711 Fielden Oct. 26, 19372,144,861 TruXell Jan. 24, 1939 2,223,755 Dillstrom Dec. 3, 19402,258,055 ;Hol10way et a1. Oct. '7, 1941 2,272,094 Murphy Feb. 3, 194242,420,164 .Bremser May 6, 1947

